Measurement of the branching fractions of $ \overline{B} $ → D$^{(*)}$K$^{−} {K}_{(S)}^{\left(\ast \right)0} $ and $ \overline{B} $ → D$^{(*)} {D}_s^{-} $ decays at Belle II

Le résumé fourni par la source

We present measurements of the branching fractions of eight $ {\overline{B}}^0 $ → D$^{(*)+}$K$^{−} {K}_{(S)}^{\left(\ast \right)0} $, B$^{−}$ → D$^{(*)0}$K$^{−} {K}_{(S)}^{\left(\ast \right)0} $ decay channels. The results are based on data from SuperKEKB electron-positron collisions at the Υ(4S) resonance collected with the Belle II detector, corresponding to an integrated luminosity of 362 fb$^{−1}$. The event yields are extracted from fits to the distributions of the difference between expected and observed B meson energy, and are efficiency-corrected as a function of m(K$^{−} {K}_{(S)}^{\left(\ast \right)0} $) and m(D$^{(*)} {K}_{(S)}^{\left(\ast \right)0} $) in order to avoid dependence on the decay model. These results include the first observation of $ {\overline{B}}^0 $ → D$^{+}$K$^{−} {K}_S^0 $, B$^{−}$ → D*$^{0}$K$^{−} {K}_S^0 $, and $ {\overline{B}}^0 $ → D*$^{+}$K$^{−} {K}_S^0 $ decays and a significant improvement in the precision of the other channels compared to previous measurements. The helicity-angle distributions and the invariant mass distributions of the K$^{−} {K}_{(S)}^{\left(\ast \right)0} $ systems are compatible with quasi-two-body decays via a resonant transition with spin-parity J$^{P}$ = 1$^{−}$ for the K$^{−} {K}_S^0 $ systems and J$^{P}$ = 1$^{+}$ for the K$^{−}$K*$^{0}$ systems. We also present measurements of the branching fractions of four $ {\overline{B}}^0 $ → D$^{(*)+} {D}_s^{-} $, B$^{−}$ → D$^{(*)0} {D}_s^{-} $ decay channels with a precision compatible to the current world averages.[graphic not available: see fulltext]

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